Temperature sensor system, radar device and method

ABSTRACT

A radar device ( 100 ) is described that includes at least one transceiver ( 205 ) configured to support frequency modulated continuous wave (FMCW); a digital controller ( 262 ); and a temperature sensor system comprising a plurality of temperature sensors ( 222, 232, 242 ) coupled to various circuits ( 220, 230, 240 ) in the at least one transceiver ( 205 ). The digital controller ( 262 ) of the radar device ( 100 ) is configured to monitor a temperature of the various circuits ( 220, 230, 240 ) by polling temperature values of the plurality of temperature sensors ( 222, 232, 242 ).

FIELD OF THE INVENTION

The field of the invention relates to a temperature sensor system for afrequency modulated (FM), such as a FM continuous wave (FMCW) radardevice, and a method therefor.

BACKGROUND OF THE INVENTION

Automotive Radar systems often consist of a multi-chip solution,combining a radar transceiver (TRx) integrated circuit (IC) and amicrocontroller unit (MCU) IC. As safety is a main concern for suchautomotive radar systems, several types of sensors are also integratedin such multi-chip solutions to ensure that the radar device isfunctioning in safe operating conditions. In such applications,temperature sensors and related temperature sensor systems are ofparticular importance, since they can detect if the device is operatingwithin a safe temperature range.

In a radar device transceiver, it is important to accurately sense thetemperature independently of the radar device state. Two modes/states ofoperation for temperature sensing are employed: an IDLE state where nointernal clock is available and all other functional states where aninternal clock is available. The way that the temperature system ismanaged and monitored in each mode is, thus, different. A typicaltemperature sensor system includes both analog and digital parts (oftenseparate integrated circuits) in order to provide good accuracy andprogrammability. Radar systems have specified an over-temperatureshutdown operation with programmable thresholds for a majority of theradar device's functional states. The temperature tracking andover-temperature shutdown is typically viewed as a four step process,including: sensing, converting, digitizing, and reading. If anover-temperature is detected, a shutdown is proceeded to cool down thechip. When several sensors are used, particularly temperature sensors,the inventors of the present invention have recognized and appreciatedthat the temperature sensor system in an FMCW radar device, andparticularly when switching between sensors, may disturb thefrequency-modulated continuous wave (FMCW) modulation waveformstransmitted and received by the radar device. Such temperature sensordisturbances create glitches in the FMCW modulated signal and disturbthe FMCW chirp linearity, thereby compromising the radar performance andtarget detection.

US 2015/0241553 A1 describes a radar data processing system that employsseveral sensors, including one or more temperature sensors used formonitoring the temperature. It ensures that the transmitter is operatingwithin the approved operating conditions.

US 8970234 B2 describes a threshold-based temperature-dependentpower/thermal management concept with temperature sensor calibration.Temperature readings from a temperature sensor are measured and reportedto a power management unit. This unit may be configured to periodicallycompare temperature readings from the temperature sensing units and mayperform control actions to ensure that an IC is within the designatedthermal limits, to avoid heat related damage.

Accordingly, it is important to provide temperature sensing whilstgenerating or processing modulation signals for FMCW radar devices,without creating glitches in the FMCW modulated signal and disturbingthe FMCW chirp linearity.

SUMMARY OF THE INVENTION

The present invention provides a FM radar device, a temperature sensingsystem for such a FM radar device, and a method therefor as described inthe accompanying claims. Specific embodiments of the invention are setforth in the dependent claims. These and other aspects of the inventionwill be apparent from and elucidated with reference to the embodimentsdescribed hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details, aspects and embodiments of the invention will hedescribed, by way of example only, with reference to the drawings. Inthe drawings, like reference numbers are used to identify like orfunctionally similar elements. Elements in the figures are illustratedfor simplicity and clarity and have not necessarily been drawn to scale.

FIG. 1 illustrates a simplified block diagram of a radar device, adaptedin accordance with examples of the invention.

FIG. 2 illustrates a high-level temperature sensor example block diagramof a radar device, in accordance with examples of the invention.

FIG. 3 illustrates a simplified flowchart of a temperature sensorsystem, in accordance with examples of the invention.

FIG. 4 illustrates a temperature sensor example block diagram of a radardevice, in accordance with examples of the invention.

FIG. 5 illustrates an example flow diagram of a radar device, forexample for the temperature sensor example block diagram of FIG. 4, inaccordance with examples of the invention.

FIG. 6 illustrates an example of an IDLE state temperature measurement,in accordance with examples of the invention.

FIG. 7 illustrates an example of a timing diagram in an MILE statetemperature measurement, in accordance with examples of the invention.

FIG. 8 illustrates an example of a Functional state temperaturemeasurement, in accordance with examples of the invention.

FIG. 9 illustrates an example of a timing diagram in a Functional statetemperature measurement, in accordance with examples of the invention.

FIG. 10 illustrates a simplified flowchart of an over-temperatureshutdown, in accordance with examples of the invention.

FIG. 11 illustrates an example of a timing diagram in a Functional statetemperature measurement during an over-temperature shutdown, inaccordance with examples of the invention.

DETAILED DESCRIPTION

In accordance with some example embodiments of the present invention,there is provided a FM, or more particularly a FMCW, radar unit that hasmultiple temperature sensors that are monitored by polling. Inparticular, when switching to an IDLE mode of operation from a FMCW modeof operation, one temperature sensor is selected and the sensor pollingoperation is halted. In this manner, timing glitches when switchingbetween sensors, particularly in an FMCW radar device, may besubstantially avoided.

Although examples of the invention are described with respect to FMCWradar systems, it is envisaged that examples of the invention may beused with any kind of frequency modulation (FM) technique (FM, FMCW,FMCW-frequency shift keyed (FSK)) that is sensitive to glitches. Thedescribed temperature sensor system, having several sensors and commoncircuitry to reduce die area, may be used in any type oftemperature-sensitive, sensor-based device. In order to read values ofall sensors used, a polling method is proposed. Furthermore, the pollingtechnique described herein may be extended to any system or device thatemploys temperature sensors where it is advantageous to avoidcontinuously monitoring sensor values.

Examples of the invention describe a radar device that includes at leastone transceiver configured to support frequency modulated continuouswave (FMCW); a digital controller; and a temperature sensor systemcomprising a plurality of temperature sensors coupled to variouscircuits in the at least one transceiver. The digital controller isconfigured to monitor a temperature of the various circuits by pollingtemperature values of the plurality of temperature sensors. The conceptof ‘polling’ in examples of the invention encompasses a process where acontroller consecutively triggers or accesses one (or more) from aplurality of sensor measurements, and particularly a temperature sensorvalue. In this manner, multiple temperature sensors and multipleconcurrent sensor measurements can he monitored using a singleprocessing pipeline whereby each of the plurality of measuredtemperature values is individually and repetitively polled.

In sonic examples, the temperature sensor system may include amultiplexer operably coupled to the digital controller and configured toselect a single temperature value from the plurality of temperaturesensors in a polling operation. In some examples, the temperature sensorsystem may include a single buffer operably coupled to the multiplexerand configured to provide a gain and DC level adjustment to a singleoutput from the multiplexer across each temperature value. In someexamples, the digital controller may be configured to monitor at leastone temperature of the plurality of temperature sensors in both ananalog domain and a digital domain.

In some examples, the digital controller may be configured to halt thepolling operation of the plurality of temperature sensors upon thedigital controller determining that the radar device is switched to anIDLE mode of operation from a FMCW mode of operation. In some examples,the digital controller may be configured to monitor a temperature in anIDLE mode of operation, where a selected temperature value is stored andread using a serial peripheral interface, SPI, clock. In some examples,the temperature sensor system may include a switch configurable toprovide an analog temperature measurement value to an output pin whenthe radar device is switched to an IDLE mode of operation from a FMCWmode of operation. In some examples, the digital controller may selectwhich temperature sensor measurement to provide to the output pin uponthe radar device switching to an IDLE mode of operation.

In some examples, the temperature sensor system may include a singleanalog to digital converter, ADC, operably coupled to a register andconfigured to convert a polled analog temperature value of one of theplurality of temperature sensors to a digital format and store thedigital representation of the temperature value in the register. In someexamples, the single ADC may support analog to digital conversion of aplurality of temperature sensor values over at least two differentranges, whereby a first temperature range is configured to provide moreresolution than a second temperature range in order to improve accuracyat the hot temperatures (e.g. In the first temperature range). In thismanner, an accurate and flexible temperature sensor system in a radartransceiver is provided that includes temperature tracking andover-temperature shutdowns.

In examples of the invention, several sensors enable the temperature atdifferent location of the chip to be known, with the possibility to readthe information both in analog and digital form. A mechanism to supporta digital reading of a temperature (from multiple temperature sensors)is beneficial to storing an image of the temperature in a register ormemory. Additionally, in some examples, a provision of an analog voltage(termed ‘SENSE’ hereafter) of the raw (analog) information concerningthe temperature may be advantageously measured and monitoredindependently from the digital code. This provides a useful back-upassessment of the device's temperature, for example should one or moreof the following occur: the register is corrupted, the SPI connection isbroken or busy, or if the Sensor ADC has developed a problem.

Referring now to FIG. 1, a simplified block diagram of a radar device100 operating at millimeter (MMW) frequencies is illustrated, inaccordance with examples of the invention. The radar device 100 containsone or several antennas 102 for receiving radar signals 121, and one orseveral antennas 103 for transmitting radar signals 121, with onerespective antenna shown for each for simplicity reasons only. Thenumber of antennas 102, 103 used may depend on the number of radarreceiver and transmitter channels that are implemented in a Oven radardevice. One or more receiver chains, as known in the art, includereceiver front-end circuitry 106, effectively providing reception,frequency conversion, filtering and intermediate or base-bandamplification, and finally an analog-to-digital conversion. In someexamples, a number of such circuits or components may reside in signalprocessing module 108, dependent upon the specific selectedarchitecture. The receiver front-end circuitry 106 is coupled to thesignal processing module 108 (generally realized by a digital signalprocessor (DSP)). A skilled artisan will appreciate that the level ofintegration of receiver circuits or components may be, in someinstances, implementation-dependent.

A controller 114, for example in a form of a microcontroller unit (MCU),maintains overall operational control of the radar device 100, and insome examples may comprise time-based digital functions (not shown) tocontrol the timing of operations (e.g. transmission or reception oftime-dependent signals, FMCW modulation generation, etc.) within theradar device 100. The controller 114 is also coupled to the receiverfront-end circuitry 106 and the signal processing module 108. In someexamples, the controller 114 is also coupled to a memory device 116 thatselectively stores operating regimes, such as decoding/encodingfunctions, and the like.

As regards the transmit chain, this essentially comprises a poweramplifier (PA) 124 coupled to the transmitter's one or several antennas103, antenna array, or plurality of antennas. In radar device 100, radartransceiver topology is different from traditional wirelesscommunication architectures (e.g. Bluetooth™ WiFi™ etc.), as modulationoccurs within a phase locked loop (PLL) (typically via a fractional-Ndivider), and is applied directly to the PA 124. Therefore, in someexamples, the receiver front-end circuitry 106 and transmitter PA 124are coupled to frequency generation circuit 130 arranged to providelocal oscillator signals. The generated local oscillator signals arethus modulated directly to generate transmit radar signals, and alsoused to down-convert received modulated radar signals to a finalintermediate or baseband frequency or digital signal for processing in areceive operation.

In accordance with examples of the invention, at least one transceiverof the radar device 100, for example including at least one transceiver,is configured to support frequency modulated continuous wave (FMCW). Atemperature sensor system 118 includes a plurality of temperaturesensors coupled to various circuits in the at least one transceiver. Thedigital controller 114 is configured to monitor a temperature of thevarious circuits by polling temperature values of the plurality oftemperature sensors, as described with reference to, inter alia, FIG. 2.

In FIG. 1, a single signal processor 108 or single microcontroller unit(MCU) 114 may be used to implement a processing of received radarsignals. Clearly, the various components within the radar device 100 canbe realized in discrete or integrated component form, with an ultimatestructure therefore being an application-specific or design selection. Askilled artisan will appreciate that the level of integration ofcircuits or components may be, in some instances,implementation-dependent.

Referring now to FIG. 2, a high-level temperature sensor example blockdiagram of a radar device 200 is illustrated in accordance with examplesof the invention. The radar device 200 is composed of a radartransceiver 205 that includes a power management function 210, which maybe in a form of a power management IC, and one or more receivers 220,frequency synthesizers 230, transmitters 240. Each of the one or morereceivers 220, frequency synthesizers 230, transmitters 240, may includeone or more respective temperature sensors 222, 232, 242 coupled to atemperature sensor system 270. The radar transceiver 205 also includes adigital part, which may be in a form of a digital IC 260, which includesa digital controller 262, such as MCU 114 from FIG. 1 operably coupled261 to a storage device 264, such as registers and/or memory. The powermanagement function 210 generates reference currents and voltages thatare needed within radar device 200.

The frequency synthesizers 230 include all the function related togeneration of the reference frequencies. The transmitters 240 containthe functionality related to the emitted signal, whilst the receivers220 are dedicated to the reception and conversion of the reflectedreceived radar signal. Amongst all the sensors implemented (with only afew potential sensors illustrated in FIG. 2 for simplicity purposesonly), the temperature sensor system 270 is configured to sense anoperating temperature at different locations of the radar transceiver205. In this example, the digital controller 262 takes the values fromthe temperature sensor system via bus 272. These values are stored inthe registers of the storage unit 264. These values can also be read bythe user via the serial peripheral interfaces (SPIs) 280, and SPI 258associated with the MCU 250, via bus 265. The digital controller 262 ofthe radar transceiver 205 is also directly connected to SPI 280. The MCU250 includes a processing unit 252, a storage unit 254, a digitalcontroller 256 and SPI 258 to communicate with the radar transceiver205.

The stored values may also be compared to programmable thresholds (notshown). If a stored value is, say, higher than a threshold it mayindicate that there is an over-temperature on the IC. In this instance,a flag is generated by the digital controller 262 and the faultcondition stored in a fault register via path 263. As the IC shouldoperate in safe conditions, a shutdown may be proceeded with in thissituation.

In a shutdown situation, the digital controller 262 sends the ICs into apower-save mode in order to cool down the chip. In a typical example,receivers 222 and transmitters 242 are powered down, whilst frequencysynthesizers 232 and power management function 210 are placed into a lowpower mode via control signals sent on path 269. Also, in some examples,a flag 285 (from a number of potential flags 281), may be sent from thedigital controller 262 to the interrupt (INT) pin 286 via an ‘OR’ logicgate 282 to indicate externally that an interrupt event has happened.The analog value from the temperature sensor system can then also berouted and measured on a SENSE pin 288 through, say, a multiplexer 284.

In accordance with examples of the invention, the radar device includesat least one transceiver 205 configured to support frequency modulated(FM) radar signals, such as FMCW radar signals, and digital controller262. Temperature sensor system that includes a plurality of temperaturesensors 222, 232, 242 coupled to various circuits such as transmitter240, receiver 220, frequency generation circuit 230. The digitalcontroller 262 is configured to monitor a temperature of the variouscircuits by polling temperature values of the plurality of temperaturesensors 222, 232, 242. In some examples, the digital controller 262 maybe configured to stop the polling of sensor temperature values when aFMCW ramp process is started; and re-start the polling of sensortemperature values following a completion of an FMCW signal generationand reception process. In some examples, the multiplexer 284 undercontrol of the digital controller 262 may be configured to select asingle temperature value from the plurality of temperature sensors 222,232, 242 in a polling operation.

The MCU 250 includes a processing unit 252, a storage unit 254, adigital controller 256 and SPI 258 in order to communicate with theradar transceiver 205. The processing unit 252 is responsible for thedigital signal processing of the data received from the radartransceiver 200, this data being, say, representative of a radar targetspeed, distance or speed variation. The storage unit 254 is the generalmemory of the MCU 250 that is responsible for both dynamic data storage(random access memory (RAM) and/or flash memory) as well as read onlymemory (ROM) (static) data storage. The digital controller 256 is incharge of the communication between all MCU different blocks and units,together with sequencing all the process (state machine) for the correctoperation of the MCU 250.

Referring now to FIG. 3, a temperature sensor flowchart 300 ispresented, according to the different operational states supported bythe radar device, such as radar device 100 of FIG. 1. In this example,prior to a first use, a trim flow operation in 302 is performed for theradar transceiver IC. A skilled person will appreciate that trimming maybe performed as there are two types of variations that any IC may besubjected to that could affect its performance (or affect theperformance uniformity across multiple same IC): process and mismatchvariations. Therefore, in order to reduce the impact on the temperaturetransfer function of such process and mismatch variations between ICs, atrimming flow selects the best value of the relevant parameters thatcompensates for such variations, prior to first use. In this manner, theaccuracy of the performance of the temperature sensors across multipleICs and batches may be better guaranteed/matched.

After the trim flow operation in 302, the radar system is ready at 304),which means that the temperature sensor system is fully ready tooperate. In this example of a temperature sensor flowchart 300, twomodes are differentiated. The first mode of operation 306 is a radardevice in an IDLE state 308, where there is no internal clock available310. Thus, an SPI clock is required for the temperature tracking,storage and reading of the values in 312. The IDLE state is the safestin terms of functionality and the lowest in terms of power consumption,which means that there is no need of an over-temperature shutdown inthis particular state.

In the second mode of operation 314, the various operations of the radardevice are grouped into all the remaining functional states of the radarsystem in 316. Temperature tracking is also performed in this mode at320. The main difference with the first IDLE mode is that an internalclock is available, and thus the temperature sensed values are polledand periodically stored. Furthermore, the stored temperature sensedvalues can also still be read via the SPI. The over-temperature shutdownoperation is required and automatically checked at 320 too.

Referring now to FIG. 4, a temperature sensor example block diagram 400of a radar device is illustrated, in accordance with examples of theinvention. As illustrated, the temperature sensor example block diagram400 includes, inter alia, four primary operational circuits/units: asensing unit 270, a converting unit 450, a digitizing unit 260 and areading unit 440. Ideally, a temperature sensor system has to deal withthe following trade-offs:

provide high accuracy (for both temperature tracking and programmableover-temperature shutdown), support in both analog and digital circuitsin order to read the sensed temperature, limit the area taken on thechip to implement temperature sensing, as well as have low currentconsumption in order to avoid self-heating and power dissipation.

In some examples, the sensing unit 270 is composed of two stages: afirst stage includes a number of, for example, two-diode based sensors422, 424, 426, although other sensors can be used. A differential signalis amplified and converted to a single-ended signal. This first stage isshared between each temperature sensor (T_SENS1 . . . T_SENS3) 422, 424,426. A multiplexer 284 is configured to select one signal (or value)from the first stage in a polling operation between multiple selectabletemperature signals (or values), based on a temperature sensor selectcontrol signal 474 and provides a single V_(single) signal to a secondstage, which in this example is a buffer 470. This second (buffer 470)stage is advantageously common for all the temperature sensors, in orderto save area and reduce current consumption. In this example, the secondbuffer 470 stage performs both amplification and DC level adjustment. AV_(sense) signal 471 output from the second buffer 470 stage is input toa sensor analog-to-digital converter (ADC) 490 in order to convert theanalog data into a digital form. In some examples, a Flash-like ADC maybe used, for example with two different ranges, whereby one range isconfigured to provide more resolution than the other range in order toimprove accuracy at the hot temperatures.

In this manner, multiple temperatures are measured at differentlocations of the chip where a useful and significant portion ofcircuitry may be shared across all temperature sensors, e.g. the buffer470 and sensor ADC 490, with just one temperature measurement beingselected. In this example, the sensor ADC 490 is a single input ADC tolimit the chip area used. A Flash-like structure for the ADC is chosento be able to perform the analog-digital conversion even without aclock, in order to facilitate temperature measurements being monitoredeven in an IDLE state. Thus, in this example and even when there shouldbe minimal heat generated in an IDLE state, it is possible to monitorpotential problems, such as the circuit being again re-started with astill too-high temperature after an over-temp shutdown. The sensor ADC490 uses a reference voltage V_(ref), for example provided by aregulator in the power management unit 210. In some examples, at theoutput of the sensor ADC 490, a thermometric code is used to transferthe data into a digital form. The digitizing unit 260 performs a numberof different operations. Firstly, the thermometric code is convertedinto a binary code, equivalent to, say, 6.5 bits in this example. As theflash-like sensor ADC 490 has, in some examples, two ranges withdifferent resolutions, the slope of the code (in temperature) may not belinear. A linearization may thus be performed, providing, say, a codewith 8 bits. This 8-bit digital value is then stored into a register,such as storage device 264 of FIG. 2. The reading unit 440 is configuredto read an image of the temperature, which is advantageously possible tobe read in analog form, by routing the V_(sense) signal 471 on a pin(SENSE pin) 473, as well as the digital stored value being readable indigital form.

Referring now to FIG. 5, an example trimming flow diagram 500 for atemperature sensor of a radar device, for example for the temperaturesensor example block diagram of FIG. 4, is illustrated in accordancewith examples of the invention. First, a regulator providing thereference voltage V_(ref) is trimmed in 505. The goal of trimmingV_(ref) is to obtain a low spread on this voltage used by the ADC, suchas sensor ADC 490 of FIG. 4. Then, the ADC is characterized throughtesting, in order to determine precisely its input range in 510, definedby its minimum input voltage V_(bottom) and its maximum input voltageV_(rep). In this example, the current injected in the diodes of theT_SENS are then trimmed in 515, in order to adjust a slope intemperature. In 515, the DC level may also be trimmed though a buffer,such as buffer 470 of FIG. 4. In this manner, it may be ensured that theV_(sense) voltage is inside the previously measured ADC input range.Finally, a fine digital trimming operation may be performed in thedigitizing unit, such as in digitizing unit 462 in FIG. 4, in 520.

Referring now to FIG. 6, an example operation of the temperature sensorexample block diagram 400 of a radar device of FIG. 4, showing an IDLEstate temperature measurement 600, is illustrated, in accordance withexamples of the invention. Like reference numbers are used in thedrawings to identify the same functional, or functionally similar,elements. In this example, the temperature measurements in an IDLE stateuse an SPI clock provided from or via SPI 608, as no internal clock isavailable.

The selection of the temperature value is made through the multiplexer284 that outputs one temperature sensor value, depending on theTemp_sensor_sel control signal 474, which in this example is controlledby an SPI writing operation 610. If the user of the radar device wantsto measure the V_(sense) analog voltage, the switch 472 that routes thevoltage on the SENSE pin 440 is closed. In this example, this operationis also performed by an SPI writing operation 612 with an instruction toclose the switch 472. Also, in this example, in order to obtain thedigital value of the selected temperature sensor, it is possible toactivate or select an SPI read operation at 614. One of several risingedges of the SPI read sequence may be used to initiate the thermometricto binary conversion, the linearization via 614, the storage of thedigital value in a dedicated register via 616, and/or sending the storedvalue to the user via 618.

Referring now to FIG. 7, an example of a timing diagram 700 in an IDLEstate temperature measurement is illustrated, in accordance withexamples of the invention, for example as may be performed in thecircuit of FIG. 6. Timing diagram 700 includes the timing of thetemperature sensor select (Temp_sensor_sel) signal 710, any commands 720from the SPI and the content of the register Sensor_adc_reg 722. In anIDLE state, the register Sensor_adc_reg 722 is dedicated to store thedigital value of the selected temperature sensor. By default,temperature sensor 1 is selected (with a binary code “01” (inTemp_sensor_sel signal 710) for the multiplexer, such as multiplexer 284from FIG. 6). In this example, an SPI reading 722 of the Sensor_adc_reg730 is performed: the value (temp1_code 732) is stored and sent 734 tothe user. Then the temperature sensor 2 is selected 724 (with a binarycode “10” (in Temp_sensor_sel signal 710) for the multiplexer) and thevalue (temp2_code 736) is stored. As an SPI command is composed ofseveral clock cycles, when the selection of temperature sensor 2 724 isapplied, one of the clock cycles of the SPI also updates the value inthe Sensor_adc_reg 730. With another SPI command, the temperature codeof temperature sensor 2 is sent 738 to the user. Subsequently,temperature sensor 3 is selected (with binary code “11” (inTemp_sensor_sel signal 710) for the multiplexer) and the value(temp3_code 740) is stored. It is sent 742 to the user with another SPIcommand.

In examples of the invention, when the radar device is generating orreceiving an FMCW modulation, the temperature sensor system is handleddifferently. The dynamic signals that control the multiplexer 284 in theanalog part of the chip (which perform sensor polling) must be avoided.The use of polling avoids the pollution of the modulation, generate someglitches, disturb FMCW chirp linearity, which compromises the radarperformances and target detection. Referring now to FIG. 8, an exampleof a functional state temperature measurement 800 is illustrated inaccordance with examples of the invention. Like reference numbers areused in the drawings to identify the same functional, or functionallysimilar, elements. In this example, an internal clock in the digitalpart is available. Also, in this example, the Temp sensor sel controlsignal 474 is periodically updated to automatically change (pollbetween) the selected temperature sensor 422, 424, 426. In this example,sensor polling between the sensors is performed using a(Temp_sensor_sel) control signal 810 initiated by digital controller262. In this example, all the digitizing operations via. 814 and thestorage of the digital value(s) via 816 are also automatically performedusing this internal clock. The SPI is still used to read thetemperature: either to route the selected temperature value(s) viaswitch 472 in response to control signal 812 the V_(sense) voltage onthe SENSE pin 440, or to read the stored digital value and sending thestored value to the user via path 818.

Referring now to FIG. 9, an example of a timing diagram 900 forfunctional state temperature measurements is illustrated, in accordancewith examples of the invention. In these functional states, a timerregulated by the, say 60 MHz, internal clock 905 is started (noting thatFIG. 9 is not to scale). The timing diagram 900 includes an indicationof the content of temperature sensor registers 920, 922 or 924, theapplication of temperature thresholds 930, 932, 934 and the status ofrespective temperature flags 940, 942, 944, as hereinbefore described.

In this example, every 10 μs 912 a different temperature sensor (T_SENS1. . . T_SENS3) in this example is selected. The different temperaturesensor selection constitutes, in examples of the invention, sensorpolling. At the end of the 10 μs timer period, the digital value of theselected temperature sensor is stored into a dedicated register. Temp1,Temp2 and Temp3 are the registers 920, 922 or 924 respectivelycorresponding to the digital values of temperature sensor 1, 2 and 3. Inexamples of the invention, the registers 920, 922 or 924 areperiodically and automatically updated.

The value in each register 920, 922 or 924 can be read 952, 954, 956 atany moment by using the appropriate SPI command 950. Thus, thetemperature code of any of temperature sensors 1 . . . 3 is obtainableby reading the Temp1 . . . Temp3 registers, where the value read may besent to the user.

An over-temperature shutdown check may also be configured to run inparallel with the temperature measurement. At the end of each 10 μstimer, a check 931, 933, 935 is made to evaluate if the stored digitalvalue is above a programmable threshold 930, 932, 934 respectively, inan over-temperature process. The check consists of comparing the valuein, say, Temp1 register 920 to the Temp1_threshold value 930 (and so onfor Temp2 and Temp3). If the value is below the threshold, the ICcontinues to work normally, because this indicates that it is in a safetemperature operating range. If the value stored is above the threshold,a flag, such as Temp1_flag 940, Temp2_flag 942, or Temp3_flag 944, isgenerated. In the example in FIG. 9, it is assumed that the temperaturesensed by temperature sensor 1 becomes locally higher in the chip,leading to the generation of Temp1_flag 940. This flag indicates that ashutdown must be commenced. In some examples, the threshold levels maybe programmable by the user using an SPI command 950. In some examples,the threshold levels may be the same or different for each temperaturesensor and may be dynamically changed/re-programmed at any time, ifneeded.

It is envisaged that tracking a temperature via a temperature sensor andperforming an over-temperature shutdown may be achieved in a number ofenvisaged different ways, with different implementations. In accordancewith the examples illustrated in FIGS. 4, 6 and 8, with the solution toperform a polling of all sensors and taking into account a typicaldevice state, IC area available, accuracy required and covering alloperational states (IDLE, functional, etc.) and a sufficient number andvariety of sensors, provide the opportunity to use a single buffer 470and a single sense ADC 490. In this manner, an advantageous trade-off ofmany operational factors may be achieved by use of the sensor polling,in order to not pollute the FMCW ramp.

In the example topology of FIGS. 4, 6 and 8, the shutdown for eachtemperature sensor 422, 424, 426 may be made at different temperaturesdue to a use of a programmable threshold, which in some examples isindependently controlled for each temperature sensor 422, 424, 426.

Referring now to FIG. 10, a simplified flowchart 1000 of anover-temperature shutdown operation is illustrated, in accordance withexamples of the invention. As soon as the radar device is operating inany functional state at 1002, a timer managed by the digital unit startsat 1004. By default, in this example, temperature sensor 1 is the oneselected for the first functional state. When a certain number N ofclock cycles (e.g. N=600) is reached, the value of the selectedtemperature sensor is stored into the dedicated register at 1006, e.g. afirst temperature for temperature sensor 1, as in 1014. Then, the storedvalue (Temp_code) is compared to the programmable threshold value (oneper temperature sensor) at 1008. If the comparison indicates there is noover-temperature at 1008, it changes the selected temperature sensor at1010, e.g. transitions to temperature sensor 2 and starts the cycleagain at 1004. If there is an over-temperature condition at 1008, thedigital unit generates an over-temperature flag and a shutdown operationis performed at 1012. At this point, a shutdown may encompass one ormore of the following, at 1016: powering down of the receiver circuitry,powering down of the receiver circuitry, entering a low-power mode ofoperation for the frequency synthesizer(s), initiating a powermanagement mode, etc.

Referring now to FIG. 11, an example timing diagram 1100 illustrates atiming of signals during a FMCW modulation phase, in accordance withexamples of the invention. The timing diagram 1100 includes an internalclock 1105. When the ramp_on signal 1114 goes high, it signifies thatthe radar device enters into a modulation phase 1116. The timer 1112that regulates the selected temperature sensor is ignored. TheTemp_sensor_sel signal 1110 is ‘on hold’ and does not change for as longas the timer is ‘ignored’. Thus, modulation occurs without any change ofthe temperature sensor selected (i.e. there is no sensor polling). Whenthe modulation phase 1116 is finished, the ramp_on signal 1114 goes lowand the timer is effective again (i.e. sensor polling is initiated).Without the modulation phase 1116, the way the values are stored and theover-temperature checks are performed the same way as describedpreviously (FIG. 9 and FIG. 10). Thus, in this example embodiment, it isproposed to switch to the FMCW modulation phase 1116 (e.g. with atransmission of chirps) during which sensor polling is deactivated. Inthis example, sensor polling is re-instated when the FMCW modulationphase 1116 is terminated (e.g. In a silent mode with no modulation (orchirps)). In essence, it is possible to make sure before sending themodulated signal (e.g. ramp_on signal 1114 is activated) that the radardevice is not in an ‘un-safe’ operational mode, so the radar device ischecked to ensure that no malfunctioning flag is activated.

For the sake of clarity, it is noted that the temperature tracking andthe over-temperature shutdown operations may be configured to runsimultaneously, in parallel.

The inventors recognized and appreciated that when the radar device isin an IDLE state and no clock is available, a flash ADC with a highnumber of bits may be used in order to share and process data frommultiple temperature sensors. The inventors recognized and appreciatedthat, if the teaching of U.S. Pat. No. 8,970,234 B2 was used in a FMCWmodulated radar device, where a flash ADC could be used for temperaturesensors during an IDLE state when no clock is available, glitches wouldbe inherently generated that would disturb the chirp linearity andcorrupt the radar signal integrity. Thus, examples of the presentinvention propose sharing of sensors using a single buffer in a sensingunit and a single flash ADC when supporting FMCW signals through apolling of the multiple sensors at a particular sampling rate in orderto read all of the temperature sensed data. In this manner, with a useof a single buffer and a single ADC a chip-area efficiency is achievedto support several temperature sensors.

Furthermore, when an IDLE state is employed, and in order to avoid theinherent glitches that would occur with switching (polling) betweenmultiple sensors, a single temperature sensor reading is selected.Furthermore, in some examples, an accurate temperature sensor system,using a single Flash-like ADC, is achieved by means of an appropriate,and simplified, trim flow performed at different block levels.Advantageously, examples of the invention also support temperaturereading measurements in both or either of the analog domain and digitaldomain.

In the foregoing specification, the invention has been described withreference to specific examples of embodiments of the invention. It will,however, be evident that various modifications and changes may be madetherein without departing from the scope of the invention as set forthin the appended claims and that the claims are not limited to thespecific examples described above.

Furthermore, because the illustrated embodiments of the presentinvention may for the most part, be implemented using electroniccomponents and circuits known to those skilled in the art, details willnot be explained in any greater extent than that considered necessary asillustrated above, for the understanding and appreciation of theunderlying concepts of the present invention and in order not toobfuscate or distract from the teachings of the present invention.

The connections as discussed herein may be any type of connectionsuitable to transfer signals from or to the respective nodes, units ordevices, for example via intermediate devices. Accordingly, unlessimplied or stated otherwise, the connections may for example be directconnections or indirect connections. The connections may be illustratedor described in reference to being a single connection, a plurality ofconnections, unidirectional connections, or bidirectional connections.However, different embodiments may vary the implementation of theconnections. For example, separate unidirectional connections may beused rather than bidirectional connections and vice versa. Also,plurality of connections may be replaced with a single connection thattransfers multiple signals serially or in a time multiplexed manner.Likewise, single connections carrying multiple signals may be separatedout into various different connections carrying subsets of thesesignals. Therefore, many options exist for transferring signals.

Those skilled in the art will recognize that the boundaries betweenlogic blocks are merely illustrative and that alternative embodimentsmay merge logic blocks or circuit elements or impose an alternatedecomposition of functionality upon various logic blocks or circuitelements. Thus, it is to be understood that the architectures depictedherein are merely exemplary, and that in fact many other architecturescan be implemented that achieve the same functionality.

Any arrangement of components to achieve the same functionality iseffectively ‘associated’, such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as being ‘associated with’ eachother, such that the desired functionality is achieved, irrespective ofarchitectures or intermediary components. Likewise, any two componentsso associated can also be viewed as being ‘operably connected,’ or‘operably coupled,’ to each other to achieve the desired functionality.Furthermore, those skilled in the art will recognize that boundariesbetween the above described operations are merely illustrative. Themultiple operations may be executed at least partially overlapping intime. Moreover, alternative example embodiments may include multipleinstances of a particular operation, and the order of operations may bealtered in various other embodiments.

Also for example, in one embodiment, the illustrated examples may beimplemented as circuitry located on a single integrated circuit orwithin a same device. Alternatively, the examples may be implemented asany number of separate integrated circuits or separate devicesinterconnected with each other in a suitable manner. Also for example,the examples, or portions thereof, may implemented as soft or coderepresentations of physical circuitry or of logical representationsconvertible into physical circuitry, such as in a hardware descriptionlanguage of any appropriate type. Also, the invention is not limited tophysical devices or units implemented in non-programmable hardware butcan also be applied in wireless programmable devices or units able toperform the desired device functions by operating in accordance withsuitable program code. However, other modifications, variations andalternatives are also possible. The specifications and drawings are,accordingly, to be regarded in an illustrative rather than in arestrictive sense.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. The word ‘comprising’ does notexclude the presence of other elements or steps then those listed in aclaim. Furthermore, the terms ‘a’ or ‘an,’ as used herein, are definedas one, or more than one. Also, the use of introductory phrases such as‘at least one’ and ‘one or more’ in the claims should not be construedto imply that the introduction of another claim element by theindefinite articles ‘a’ or ‘an’ limits any particular claim containingsuch introduced claim element to inventions containing only one suchelement, even when the same claim includes the introductory phrases ‘oneor more’ or ‘at least one’ and indefinite articles such as ‘a’ or ‘an.’The same holds true for the use of definite articles. Unless statedotherwise, terms such as ‘first’ and ‘second’ are used to arbitrarilydistinguish between the elements such terms describe. Thus, these termsare not necessarily intended to indicate temporal or otherprioritization of such elements. The mere fact that certain measures arerecited in mutually different claims does not indicate that acombination of these measures cannot be used to advantage.

1. A radar device comprises: at least one transceiver configured tosupport frequency modulated (FM) radar signals; a digital controller;and a temperature sensor system comprising a plurality of temperaturesensors coupled to various circuits in the at least one transceiver;wherein the digital controller is configured to monitor a temperature ofthe various circuits by polling temperature values of the plurality oftemperature sensors.
 2. The radar device of claim 1 wherein thefrequency modulated radar signals are frequency modulated continuouswave, FMCW, signals and the digital controller is configured to stop thepolling of sensor temperature values when a FMCW ramp process is startedand re-start the polling of sensor temperature values following acompletion of an FMCW signal generation and reception process and theradar device switching to an IDLE mode of operation.
 3. The radar deviceof claim 1 wherein the digital controller is configured to read aplurality of temperature values of the plurality of temperature sensorsand compare at least one read temperature value with at least onetemperature threshold value, and in response to the comparison exceedinga threshold, the digital controller initiates a shutdown operation. 4.The radar device of any preceding claim 1, wherein the temperaturesensor system further comprises a multiplexer operably coupled to thedigital controller and configured to select a single temperature valuefrom the plurality of temperature sensors in a polling operation.
 5. Theradar device of claim 3, wherein the temperature sensor system furthercomprises a single buffer operably coupled to the multiplexer andconfigured to provide a gain and DC level adjustment to a single outputfrom the multiplexer across each temperature value.
 6. The radar deviceof claim 1 wherein the digital controller is configured to monitor atleast one temperature of the plurality of temperature sensors in both ananalog domain and a digital domain.
 7. The radar device of claim 6wherein the digital controller is configured to monitor a temperature inan IDLE mode of operation, where a selected temperature value is storedand read using a serial peripheral interface, SPI, clock.
 8. The radardevice of claim 6 or claim 7 wherein the temperature sensor systemfurther comprises a switch configurable to provide an analog temperaturemeasurement value to an output pin when the radar device is switched toan IDLE mode of operation from a FM mode of operation.
 9. The radardevice of claim 8 wherein the digital controller selects whichtemperature sensor measurement to provide to the output pin upon theradar device switching to an IDLE mode of operation.
 10. The radardevice of any preceding claim 1 wherein the temperature sensor systemfurther comprises a single analog to digital converter, ADC, operablycoupled to a register and configured to convert a polled analogtemperature value of one of the plurality of temperature sensors to adigital format and store the digital representation of the temperaturevalue in the register.
 11. The radar device of claim 10 wherein thesingle ADC supports analog to digital conversion of a plurality oftemperature sensor values over at least two different ranges, whereby afirst temperature range is configured to provide more resolution than asecond temperature range in order to improve accuracy at the hottemperatures.
 12. A temperature sensor system comprising: at least onetransceiver configured to support frequency modulated continuous wave(FMCW); a digital controller; and and a temperature sensor systemcomprising a plurality of temperature sensors coupled to variouscircuits in the at least one transceiver; wherein the digital controlleris configured to monitor a temperature of the various circuits bypolling temperature values of the plurality of temperature sensors. 13.A method for supporting frequency modulated (FM) radar signals, themethod comprising: monitoring a temperature of various circuits in theat least one transceiver; and receiving a plurality of temperaturemeasurements from a plurality of temperature sensors coupled to thevarious circuits; polling temperature values of the plurality oftemperature sensors; wherein at least one transceiver of a radar deviceis configured to support frequency modulated (FM).
 14. The method ofclaim 13 wherein the frequency modulated radar signals are frequencymodulated continuous wave (FMCW) signals and the method furthercomprises: stopping the polling of sensor temperature values when a FMCWramp process is started; and re-starting the polling of sensortemperature values following a completion of an FMCW signal generationand reception process.
 15. The method of claim 13 further comprisingselecting one of a plurality of stored temperature values as being arepresentative temperature.
 16. The radar device of claim 2 wherein thedigital controller is configured to read a plurality of temperaturevalues of the plurality of temperature sensors and compare at least oneread temperature value with at least one temperature threshold value,and in response to the comparison exceeding a threshold, the digitalcontroller initiates a shutdown operation.
 17. The radar device of claim3, wherein the temperature sensor system further comprises a multiplexeroperably coupled to the digital controller and configured to select asingle temperature value from the plurality of temperature sensors in apolling operation.
 18. The radar device claim 3 wherein the digitalcontroller is configured to monitor at least one temperature of theplurality of temperature sensors in both an analog domain and a digitaldomain.
 19. The radar device of claim 2 wherein the temperature sensorsystem further comprises a single analog to digital converter, ADC,operably coupled to a register and configured to convert a polled analogtemperature value of one of the plurality of temperature sensors to adigital format and store the digital representation of the temperaturevalue in the register.
 20. The radar device of claim 3 wherein thetemperature sensor system further comprises a single analog to digitalconverter, ADC, operably coupled to a register and configured to converta polled analog temperature value of one of the plurality of temperaturesensors to a digital format and store the digital representation of thetemperature value in the register.